#1976. naive fix of the eclipse compiler's error 'The target type of this expression must be a functional interface' in code like 'lombok.val foo = (System.currentTimeMillis() > 0) ? (Runnable)()-> {} : System.out::println;'

src/eclipseAgent/lombok/eclipse/agent/PatchVal.java

@@ -1,16 +1,16 @@
 /*
  * Copyright (C) 2010-2019 The Project Lombok Authors.
- * 
+ *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
- * 
+ *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
- * 
+ *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
@@ -21,8 +21,11 @@
  */
 package lombok.eclipse.agent;
 
+import org.eclipse.jdt.core.compiler.CategorizedProblem;
+import org.eclipse.jdt.internal.compiler.CompilationResult;
 import org.eclipse.jdt.internal.compiler.ast.ASTNode;
 import org.eclipse.jdt.internal.compiler.ast.Annotation;
+import org.eclipse.jdt.internal.compiler.ast.ConditionalExpression;
 import org.eclipse.jdt.internal.compiler.ast.Expression;
 import org.eclipse.jdt.internal.compiler.ast.ForeachStatement;
 import org.eclipse.jdt.internal.compiler.ast.ImportReference;
@@ -44,11 +47,13 @@ import org.eclipse.jdt.internal.compiler.lookup.TypeConstants;
 import org.eclipse.jdt.internal.compiler.lookup.TypeIds;
 
 import lombok.permit.Permit;
+import org.eclipse.jdt.internal.compiler.problem.AbortCompilation;
 
 import java.lang.reflect.Field;
 
 import static lombok.eclipse.Eclipse.poss;
 import static lombok.eclipse.handlers.EclipseHandlerUtil.makeType;
+import static org.eclipse.jdt.core.compiler.CategorizedProblem.CAT_TYPE;
 
 public class PatchVal {
 	
@@ -358,6 +363,32 @@ public class PatchVal {
 		} catch (ArrayIndexOutOfBoundsException e) {
 			// Known cause of issues; for example: val e = mth("X"), where mth takes 2 arguments.
 			return null;
+		} catch (AbortCompilation e) {
+			if (collection instanceof ConditionalExpression) {
+				ConditionalExpression cexp = (ConditionalExpression) collection;
+				Expression ifTrue = cexp.valueIfTrue;
+				Expression ifFalse = cexp.valueIfFalse;
+				TypeBinding ifTrueResolvedType = ifTrue.resolvedType;
+				CategorizedProblem problem = e.problem;
+				if (ifTrueResolvedType != null && ifFalse.resolvedType == null && problem.getCategoryID() == CAT_TYPE) {
+					CompilationResult compilationResult = e.compilationResult;
+					CategorizedProblem[] problems = compilationResult.problems;
+					int problemCount = compilationResult.problemCount;
+					for (int i = 0; i < problemCount; ++i) {
+						if (problems[i] == problem) {
+							problems[i] = null;
+							if (i + 1 < problemCount) {
+								System.arraycopy(problems, i + 1, problems, i, problemCount - i + 1);
+							}
+							break;
+						}
+					}
+					compilationResult.removeProblem(problem);
+					
+					return ifTrueResolvedType;
+				}
+			}
+			throw e;
 		}
 	}
 }

test/transform/resource/after-delombok/ValLambda.java

@@ -12,7 +12,7 @@ class ValLambda {
 	}
 	public void easyLubLambda() {
 		final java.lang.Runnable foo = (System.currentTimeMillis() > 0) ? (Runnable) () -> {
-		} : (Runnable) System.out::println;
+		} : System.out::println;
 	}
 //	public void castLubLambda() {
 //		Runnable foo = (Runnable) ((System.currentTimeMillis() > 0) ? () -> {} : System.out::println);

test/transform/resource/after-ecj/ValLambda.java

@@ -14,6 +14,6 @@ class ValLambda {
   }
   public void easyLubLambda() {
     final @lombok.val java.lang.Runnable foo = ((System.currentTimeMillis() > 0) ? (Runnable) () -> {
-} : (Runnable) System.out::println);
+} : System.out::println);
   }
 }

test/transform/resource/before/ValLambda.java

@@ -10,7 +10,7 @@ class ValLambda {
 	}
 	
 	public void easyLubLambda() {
-		lombok.val foo = (System.currentTimeMillis() > 0) ? (Runnable)()-> {} : (Runnable)System.out::println;
+		lombok.val foo = (System.currentTimeMillis() > 0) ? (Runnable)()-> {} : System.out::println;
 	}
 	
 //	public void castLubLambda() {